ABSTRACT
Rice husk, also called paddy husk or hull, is the major byproduct of rice milling process and the industry. It constitutes, on an average, about 20% by weight of paddy. With world paddy production around 745 million tonnes (FAO 2014), and around 80% of it being converted to milled rice, there is an estimated generation of about 120 million tonnes of husk the world over. This is the highest quantity of a byproduct from any industry in the food sector. Utilisation, or even disposal, of this low-value byproduct has been a challenging problem. Use or disposal has frequently proved difficult because of the tough, woody, abrasive nature of the husk, its low nutritive value, resistance to weathering, great bulk and high ash content. The problem is magnified due to its frequent accumulation and piling up at the mill site. As against the other byproducts emanating from the mill, which keep getting cleared from the mill premises continuously, husk generated generally keeps accumulating. If there is no ready off take, it poses problem of disposal. By far its traditional major use has been as boiler fuel for the production of steam in rice mills and parboiling plants. Not that attention on exploring ways and means to utilise this byproduct have been lacking. Studies on its structure, composition, properties and possibilities of its use in various industries have been reported over many decades. A good amount of literature has been generated through a large number of publications on varied potentialities for its uses, mostly at laboratory level. But commercial usage has been rather limited due to many factors. The situation, however, seems to be changing now, as many new applications are being tapped for its economic and commercial exploitation.
